Possible to "zone" a non-zoned coil unit, or "re-zone" a zoned coil? (QEE opts.)

Hi, so I’m having a lot of trouble deciding whether to buy the Quantum Edge Elite (comes with Bolsa inner coils), or the Quantum Edge Elite Combi-Zone (zoned coils) for my DIY build (2" of 24ild 3lb memory foam on top of 2" of 19ild blended Talalay). The problem lies in the fact that while I’m lighter weight and often a side sleeper (5’7" 120lb) - which usually is recommended for the Bolsa – I also have much narrower hips than shoulders, which would lead me to believe that too much sink in the hips (Bolsa) could cause unreconcilable lower back alignment issues since the overall softness has to be tuned for my broader yet less dense shoulders to sink in enough. If the coil firmness is the same throughout, I would think this could be an issue. However, I’ve been told that the Bolsa uses softer 15 gauge coils as opposed to the CZ’s 14 gauge in the shoulder area – even though Leggett & Platt’s own info sheets list softer ILD values for the shoulder region in the Combi-Zone – how frustrating! I’ve been trying to confirm with them, but they’re not answering their calls. I also feel like I’ve seen so many posts here and at r/Mattress of people complaining about those Bolsa coils being too soft and hammocking, causing alignment problems over time, but maybe these all happen to be heavier individuals, or with wider hips? Does anyone else get that sense as well, or more usefully, has anyone actually tried/compared the Combi-Zone unit or the Bolsa?

Perhaps something that could also make this decision easier would be considering the contingency plans for if the Bolsa is too soft in the middle, or if the Combi-Zone is too firm in the middle. I’m wondering if anyone here can shed light on whether zoning with transition layers above or below the coils would be an applicable method of doing this kind of “re-zoning” if needed, and whether that would be better suited to the Bolsa or Combi-Zone.

The question is if it would even be possible to add supportiveness to the Bolsa if it’s sagging too much in the middle, through something like a firmer 1 or 2" foam section above the coils, surrounded on both ends with softer material to create the zoning effect, or if the Combi-Zone could be softened in the middle section via a 1-2" layer there (though if the shoulders are already not soft enough, it would be difficult to do this kind of softening in the middle, I’d think), or if playing with the foam base layer underneath the coils would be able to change the feel/alignment in this way?

Any experience with foam zoning / either Quantum Edge Elite coil unit would be so useful here!

At your height and weight (BMI) I would definitely go for the Bolsa. It may work for some people but I find adding another zoning into the coils isn’t always the best idea (especially when you look at where it is on the mattress relative to where you’ll be sleeping). I had the combi-zone myself (which they recommended) and ended up tossing it due to the hammocking problem (however I’m near 250lbs and built like an NFL linebacker). Heavier people are almost always better off skipping the hybrid springs and going right to full latex. So if I were you I would try the Bolsa and then plan on adding zoning over that to correct any alignment issues you might have from the initial setup (you may get lucky and nail it right away). You could also use a euro slat adjustable base to try and give you more zoning as well. Zoning generally works best with solid foam mattresses but as long as you aren’t too far off with your design you can compensate some for alignment issues in hybrids too.

I’m starting to lean this way too, primarily because I don’t know if the zones in the Combi-Zone would neccesarily be placed in the exact right positions for my body, and for the reasons I mentioned about difficulties with adding “reverse-zoning” to that while maintaining the shoulder area softness.

While I have seen more posts complaining about the Bolsa unit hammocking / causing lower back alignment issues, the majority of people are above my BMI, and that construction is outright more common. I’ve also seen a few examples of people who got rid of the Combi-Zone now – and I would be very, very surprised if a top-quality coil unit from Leggett & Platt like doesn’t have enough support for a 120lb sleeper. In any case, softening it up or doing some zoning would probably be a bit more achievable starting with an even playing field of firmness.

One point of confusion though is that while L&P’s spec sheets say the Combi-Zone has a lower ILD in the shoulder region than the Bolsa, Ken from APM told me the Combi-Zone is 14 gauge (firmer) coils in the shoulder region, while the Bolsa is 15 gauge – and then Latex Mattress Factory told me the Bolsa is 16 gauge. I know L&P produces their units differently for different customers, but I would hope these units with the same names would be the same, and the rep from LMF is just confusing the inner coils with the perimeter coils on the Quantum Edge Elite, which may be 16? L&P doesn’t answer their phones, and waiting to hear back from the LMF warehouse on this.

I would trust L&P’s documentation above all else. Remember designing a spring layer isn’t as simple as just looking at the wire gauge despite what the marketing folks would have you believe (you can also put some metal in a microwave but they won’t tell you that either). Spring rates are determined by the diameter of the coil, number of wire turns and the wire gauge but that’s alot more than the average consumer can handle so marketing folks sift that down to just wire gauge for simplicity. The coil diameter also dictates how many coils per sq-ft there are in the mattress (one giant 14ga coil would feel vastly different than twenty 16ga coils). Again you biggest concern choosing the base is to ensure it provides enough support for you because it’s much easier to add more give to the upper layers than it is to compensate for lack of support. Also to me the combi-zone was a good idea on paper but the reality is that it could complicate things if the zoning doesn’t work perfectly for you (which is why I’d suggest Bolsa if you want hybrid).